Aircraft jet propulsion apparatus with thrust reversing means



Feb. 5, 1963 D. M. BROWN ETAL 3,076,309

AIRCRAFT JET PROPULSION APPARATUS WITH THRUST REVERSING MEANS FiledMafch 16. 1959 3 Sheets-Sheet 1 Feb. 5; 1963 o. M. BROWN EI'AL 3,07 ,30

AIRCRAFT JET PROPULSION APPARATUS WITH THRUST REVERSING MEANS FiledMarch 16, 1959 3 Sheets-Sheet 2 Feb. 5, 1963 n. M. BROWN ETAL :AIRCRAFTJET PROPULSION APPARATUS WITH THRUST REVERSING MEANS s Sheets-Sheet 3Filed March 16. 1959 I ll United States Patent 3,076,309 AIRCRAFT JETPROPULSION APPARATUS WITH THRUST REVERSING MEANS David Morris Brown,Alvaston, and Rowan Herbert Colley, Sunny Hill, Derby, England,assignors to Rolls- Royce Limited, Derby, England, a British companyFiled Mar. 16, 1959, Ser. No. 799,763 Claims priority, application GreatBritain Apr. 3, 1958 1 Claim. (Cl. 60--35.54)

This invention comprises improvements in or relating to aircraft jetpropulsion apparatus and is concerned more particularly with suchapparatus comprising a jet pipe with a propulsion nozzle at its outletend and means for obtaining reverse thrust, for instance for aircraftbraking purposes, which means includes a duct receiving gas from therearwardly-extending exhaust gas path and housing a vaned structure forassisting to impart to gas flowing in the duct a component of velocityin a direction reverse to the direction of flow in the jet pipe. Suchapparatus will be referred to as being of the class speci- According tothe present invention, the vaned structure of jet propulsion apparatusof the class specified comprises first vane means to assist to impart tothe gas a component of velocity in a first direction and second vanemeans extending transversely to the first vane means to assist to impartto the gas a component of velocity in a direction inclined to the firstdirection so that the reverse thrust jet issuing from the vanedstructure has components of velocity in two directions mutually at rightangles to one another and to the direction of gas flow at the entry sideof the vaned structure. For instance, where the vaned structure is in alateral duct extending from a jet pipe the first vane means may impart aforward component of velocity and the second vane means may impart avertical component of velocity, the direction of gas flow at the entryof the vaned structure beingsubstantially horizontal and laterallyof thejet propulsion apparatus.

Preferably, the first and second vane means are arranged so that the gasis acted upon simultaneously by both vane means, and in one such anarrangement the first vane means is in the form of cascades of vanesarranged side by side and separated by strip-like support members forthe vanes, and the support members are so inclined to the direction ofgas flow at the entry to the grid structure as themselves to form thesecond vane means.

Preferably, the vaned structure is so constructed and so supported inthe jet propulsion apparatus as to avoid overstressing due to thermalexpansion, and in one construction in which cascades of vanes areseparated by support members as jet set forth, some of the supportmembers are made relatively flexible as compared with other (andrelatively rigid) support members, there being a relatively flexiblesupport member next adjacent each of the relatively rigid supportmembers on each side of it, the vanes of the cascade on one side of eachrela tively rigid support member being attached to it at positions levelwith the vanes of the cascade on the other side of the support member,and the vanes of the eascade on one side of a relatively flexible memberbeing staggered lengthwise of the member relative to the vanes of thecascade on the other side of the member. Such a vaned structure may besupported in the jet propulsion apparatus along one side of the vanedstructure by rigidly securing the adjacent ends of the rigid supportmembers to a wall of the duct and along the opposite side of the vanedstructure by providing sliding connections between the rigid supportmembers and another wall of the duct.

One embodiment of this invention will now be described with reference tothe accompanying drawings in which:

FIGURE 1 is a view, with parts broken away, of an engine of an aircraft,

FIGURE 2 is a view to a larger scale in the direction of arrow 2 onFIGURE 1,

FIGURE 3 is a view in the direction of arrow 3 on FIGURE 2,

FIGURE 4 is a section on the line 4-4 of FIGURE 3, and

FIGURE 5 is a section to a larger scale on the line 5-5 of FIGURE 2.

Referring to FIGURE 1, one of the engines 12 of a multi-engined aircraftis shown diagrammatically and it comprises a compressor 14, combustionequipment 15, a turbine 16 and an exhaust assembly 17 connected in flowseries between an air intake 18 formed by the leading part of a nacelle19 housing the engine and a propulsion nozzle 20 through which exhaustgases pass to atmosphere.

The exhaust assembly 17 is arranged so that, when necessary, a reversethrust can be obtained for braking the aircraft and the means forreversing the thrust is shown as comprising a pair of jet pipe doors 21,22 pivoted about a diameter of a jet pipe 17a which connects the turbine16 with nozzle 20, to swing between a normal thrust position in whichthe doors 21, 22 blank off apertures of a vaned structure 23 in the jetpipe and permit the exhaust gases to flow to the nozzle 20, and areverse thrust position as shown in which the gases are constrained toflow through the apertures of the vaned structure 23 which assist toimpart a forward velocity component to the gases before they flow toatmosphere through apertures in the nacelle 19 as forwardly directedjets.

In order to prevent a forwardlydirected jet from the engine frominterfering with the operation of an adjacent engine, it is arrangedthat the vaned structure 23 on the side of the engine 12 adjacentanother engine causes the forwardly-directed jet issuing therefrom alsoto be deflected downwards. In some aircraft arrangements a similardeflection of all the forwardly-directed jets from an engine may benecessary for instance to avoid damage or b'ufieting of adjacentaircraft parts.

In order to obtain such' additional deflection of the jets, and also toaccommodate' relative thermal expansion without overstress'ing,atconstruction-of vaned structure as shown in FIGURES 2 to 5 may beemployed.

The vaned structure is curved (FIGURE 3) to follow the contour of thejet pipe and is shaped in the fore and aft direction (see FIGURE 3)according to the axial contours of the jet pipe 17 and nacelle 19.

The vaned structure comprises a series of cascades of guide vanes 25,each cascade comprising a row of circumferentially-short,radially-curved vanes arranged one behind the other in the fore and aftdirection as will be seen in FIGURE 4, the vanes 25 being arranged withtheir concave faces directed forwardly so that gas passing between thevanes which at the entry to the vaned structure is flowing in asubstantially horizontal direction at right angles to the fore and aftdirection, is given a component of velocity in the forward direction.The vanes are supported by fore and aft extending striplike supportmembers 26, 27, there being at least one support member 26 on each sideof a support member 27, the vanes extending circumferentially betweenthe members 26, 27.

As will be seen from FIGURES 2 and 3, the members 26- and 27 aresubstantially parallel to one another and are inclined to the radialdirection from the axis of the 3 engine so that thesemembers also act assecond vane means to deflect the gas flowing through the structure. Theinclination is selected so as to impart the desired additionaldeflection of the gases.

In order to accommodate relative thermal expansion of the parts of thegrid structure without overstressing it, the following arrangement maybe adapted.

The members 2-6 are made thinner than the members 27 so that the members26 are more flexible than the members 27. Also, as will best be seenfrom FIGURES 2 and 4, the vanes 25 of the cascade joined to one side ofeach thick member 27 are level with the vanes of the cascade joined tothe opposite side of the member, whilst .the vanes 25 of the cascadejoined to one Side of each thin member 26 are staggered in the fore andaft direction with respect to the vanes of the cascade joined to theopposite side of the thin member 26. Thus, for instance, in-FIGURE 2,the vanes 25a of the righthand cascade are joined to the right-handthick member 27a at positions level with the vanes 25b of the cascade on;the opposite side of the member 27a, and the vanes 250 .of theleft-hand cascade are joined to the letthand thin .member 26a atpositions staggered with respect to the vanes 25d on the opposite sideof the thin member 26a. Relative expansion of the vanes can thus beaccommodated in part by sinuous bending of the thin support members 26.The outer ends of the vanes 25a and 25c .are joined by thin sheet metalwalls 28.

The grid structure is supported in the nacelle in the following way. Thethick members 27 are provided at their forward ends with flanges 30which are bolted to 'facings 31 (FIGURE 2) secured on a wall 32 formingthe forward end of a duct between the apertures of the structure 23 inthe jet pipe and the apertures in the ,nacelle 19, and are provided attheir rearward ends with plug pieces 33 (FIGURE which are slidinglyreceived in sockets 34 secured to a rear wall 35 of the duct. Thus foreand aft expansion of the grid structure is permitted relative to thestructure in which it is supported.

The walls 28 are provided near their ends which are adjacent the flanges30, with bushes 37 which are aligned with sleeves 38 mounted in thewalls of the duct, and locating members 38a are provided which arethreaded into the sleeves 38 and project from the sleeves 38 to have apivotal and sliding engagement with the bushes 37.

We claim:

In jet propulsion apparatus comprising a jet pipe through which exhaustgas flows, a propulsion nozzle mounted on the jet pipe at one end andforming a first outlet for the exhaust gas, an aperture in the jet pipeupstream of the nozzle forming a second outlet, de-

flector means within the jet pipe, said deflector means having anoperative setting in which exhaust gas is deflected towards the secondoutlet and an inoperative setting in which exhaust gas flows to thepropulsion nozzle, and a vaned structure mounted in the second outletimparting to gas flowing through the second outlet a component ofvelocity in a direction opposite to the direction of flow in the jetpipe; said vaned structure comprising a plurality of first vanes spacedapart lengthwise of the jet pipe one behind the other, each first vaneextending circumferentially of the j t pipe, and each first vaneimparting to the exhaust gas said component of velocityin the directionopposite to,the direction of gas flow in the jet pipe, said first vanesbeing disposed in a number of cascades disposed side by side, and aplurality of second vanes spaced apart circumferentially of the jetpipe, the second vanes being constituted by strip members extendinglongitudinally of the jet pipe and separating the said cascades of saidfirst vanes One from the other, the strip members being interconnectedby the first vanes, the strip members being in planes inclined at anangle to the radial direction from .the

center line of the jet pipe to the mid point of the vaned structure,said second vanes acting together and deflecting the exhaust gas jetfrom said vaned structure as a whole to be inclined to a planecontaining both the jet pipe axis and said radial direction and toimpart to the gas a component of velocity in a direction at right anglesto both said radial direction and said oppositedirection, some of thestrip members being relatively flexible and other strip members beingrelatively rigid, there being at least one relatively flexible stripmember between each relatively rigid member and the adjacent relativelyrigid member, the first vanes forming the cascades attached .to eachside of each relatively rigid member being at level positions lengthwiseof the rigid member, and the first vanes of the cascade attached to oneside of a relatively flexible member being staggered lengthwise of themember relative to the first vanes of the cascade attached to the otherside of the member.

References Cited in the file of this patent UNITED STATES PATENTSFOREIGN PATENTS 754,065 Great Britain Aug. 1, 1956

